1. Field of the Invention
Aspects of the present invention relate to an apparatus and method for controlling a Universal Serial Bus (USB) operation and, more particularly, to an apparatus and method for controlling a USB operation, whereby the USB operation can be controlled without unplugging a USB cable while maintaining a charge state from a host device.
2. Description of the Related Art
FIG. 1 illustrates a Universal Serial Bus (USB) apparatus connected to a host device via a USB cable. A USB apparatus 100 is connected to a host device 150 via a USB cable 130. The USB apparatus 100 includes a USB connector 120 to which the USB cable 130 connected to the host device 150 is connected and a controller 110 including a USB controller (not shown) to determine whether the USB cable 130 is connected to the USB connector 120.
FIG. 2A illustrates the USB cable 130. FIG. 2B illustrates a structure of USB plug pins. The USB cable 130 includes a pair of data lines D+ and D− for transferring a differential signal and a pair of power lines VBUS and GND. The voltage of VBUS is generally around +5 V. As illustrated in FIG. 2B, the pins for the power lines VBUS and GND are longer than the pins for the data lines D+ and D−. Thus, when the USB cable 130 is plugged in, power is supplied before the data lines D+ and D− are connected. When the USB cable 130 is unplugged, the data lines D+ and D− are disconnected before the power is cut off so as to prevent damage to the USB apparatus 100.
In order to communicate with the host device 150 using the USB apparatus 100, a user must connect the USB cable 130 to the USB connector 120 and the host device 150. The controller 110 determines that power is input through the USB cable 130 and controls the communication using the data lines D+ and D−. When the user unplugs the USB cable 130, the controller 110 determines that the USB connection is released.
The user must plug or unplug the USB cable 130 into or from the USB apparatus 100 for establishing or discontinuing the USB connection. The USB apparatus 100 cannot be used while the USB connection with the host device 150 is maintained; for example, an application or Audio and/or Video (A/V) data stored in the USB apparatus 100 cannot be executed while the USB connection is maintained.
Typically, a port of the USB apparatus 100 into which the USB cable 130 is plugged is used as a port into which a power adapter is plugged. In order to charge the USB apparatus 100, either the user must plug the power adapter into the USB apparatus 100 after unplugging the USB cable 130 from the USB apparatus 100, or the USB apparatus 100 must forcefully release communication with the host device 150 in a state where the USB cable 130 is connected between the USB apparatus 100 and the host device 150. However, in order to communicate between the USB apparatus 100 and the host device 150 again, the user must either plug the USB cable 130 into the USB apparatus 100 after unplugging the power adapter from the USB apparatus 100 in the former situation, or the user must unplug the USB cable 130 from the USB apparatus 100 and plug the USB cable 130 into the USB apparatus 100 again in the latter situation. In order for the user to use the USB apparatus 100, the user must repeatedly plug and unplug the USB cable 130, resulting in inconvenience of use.